Aflatoxins, natural compounds toxic to human beings and animals, are the secondary metabolites secreted by Aspergillus flavus and Aspergillus parasiticus. A variety of aflatoxins exist in the world and more than 20 kinds have been identified. Aflatoxins are characterized by wide pollution, strong toxicity and severe harm etc. Therefore, at least 70 countries in the world have established maximum residue limit with regard to aflatoxins contained in agriculture products and foods. Many countries have even established maximum residue limit with regard to the total amount of those main aflatoxins such as B1, B2, G1 and G2, so the total aflatoxin analysis is very important.
The current aflatoxin assay methods include thin layer chromatography (TLC), precision instrumental analysis and immunoassay. The TLC method is the most popular for testing aflatoxins since it can be performed in general labs and no special instruments are required. However, a lot of reagents are needed for the TLC assay, the operation is complicated, and other components are liable to interfere with the test result, causing poor accuracy, uncertain dosing and harm to operators and the ambient environment, which makes it unsuitable for quick on-site inspection. The precision instrumental analysis includes fluorescence spectrophotometry and high performance liquid chromatography (HPLC) characterized by high sensitivity and accuracy. However it is also unsuitable for quick inspection considering the expensive instruments, high purity requirement for aflatoxin samples, complicated and time consuming sample pre-processing and strict testing environment requirements. The immunoassay technology developed in recent years can help to avoid the shortcomings of the former two methods since it is characterized by good specificity, high sensitivity, simple pre-processing, low cost, less harm to operators and the ambient environment, and is suitable for on-site and batch inspection etc.
The immunoassay is adopted for qualitative and quantitative detection of ultra-micro residues based on the specific reaction of antigens and antibodies as well as the biological, physical or chemical magnification of antigen (or antibody) markers. For any immunoassay techniques with respect to total aflatoxin analysis, the antibody against total aflatoxins B1, B2, G1 and G2 are required. In fact, many reports regarding development of antibodies for anti-aflatoxins have been published worldwide. Further, all-purpose antibodies (polyclonal antibodies) against aflatoxins have also been reported. Moreover, some scientists have established total aflatoxin assay for aflatoxins based on the all-purpose anti-aflatoxin antibody. The all-purpose anti-aflatoxin antibody mainly features a strong, specific binding reaction with different aflatoxins and can be used for establishing immunoassay for any of the different aflatoxins. While the antibodies against total aflatoxin B1, B2, G1 and G2 feature not only strong specific binding reactions with different aflatoxins, but also, particularly, stronger sensitivity consistency with regard to the immunoassay for each aflatoxin. The all-purpose antibody mentioned in current reports published both domestically and abroad for anti-aflatoxins shows high versatility, but as for each separate aflatoxin, the sensitivity consistency of the assay is poor. Thus, the all-purpose antibody mentioned in these reports is not suitable for establishing the total aflatoxin assay for aflatoxins B1, B2, G1 and G2. Even if method of total aflatoxin assay is established based on those all-purpose antibody, the quantitative accuracy will be poor. Therefore, the development of antibodies against total aflatoxin B1, B2, G1 and G2 is very important for quick quantitative immunoassay of the total amount of aflatoxin B1, B2, G1 and G2.